Bachmann 70 ton and ERR mini commander coupler

The MC-II drives one 20ma LED directly, no resistors needed.  A bog standard five cent white or warm-white LED does it fine.  The physical size of the LED doesn't matter as far as the drive current, so pick the size that fits your application. 

The MC-II drives the standard Lionel electrocoupler, it should measure about 5-7 ohms.  Do not try to use an MTH PS2/PS3 coupler, those are too low impedance.

Sound will be a problem as you will have the prime mover at full RPM all the time, and of course, you won't have command control of the horn or bell.  I'd recommend biting the bullet and going with an ERR sound board.  The MC-II does have a serial data output to drive the standard ERR sound board.

Thanks John

Do you have a warm white digikey number (or series) handy.

I don't have numbers handy, simply because I buy my LED's in bulk, many times on eBay or other overseas vendors.  I'll buy several hundred of a type dirt cheap.  If they look really good, I'll use them.  If I don't like the color, I'm only out a few bucks, and I stuck them in a big backup box in case I ever find a need.  Depending on the specific application, I use amber, warm-white, or bright white for headlights.  Usually, they're either 3mm or 5mm, though a couple headlight applications have used 2mm post LED's.  I also use the flangeless LED's for most headlights, they mimic the 3mm bulbs that I'm typically replacing.

Of course, I also use red, yellow, green LED's in various sizes, and even the bi-color LED's in two and three lead types.  Flashing,  flickering, and surface mount LED's round out the collection.

To give you an idea, here's one of my two LED parts boxes, probably at least a couple thousand LED's in there.

You can probably tell, I like lights on my trains!

When you go looking pick the size you'll need.  Here's a search for warm white flangeless LED. to get you started.

The reason I was going to use the Bachmann sound is size and mounting of speaker and impedance match plus there isn't much room in the hood for electrinics.  May have to mount sideways to fit.  Small engines are definitely a challenge.  The speaker is in a relatively small fuel tank. 

This is the first, once I get things worked out, the possiblilitys are endless as NC was loaded with 70 tonners at one time.

Similar ERR upgrade, Rich Yoder GE 44 tonner, with Sound and electro-couplers.  Click on the link posted, Upper left corner, you may have to click on Slideshow.   Speaker 8 ohm, wafer, and couplers (modified) were from Atlas. 

I managed to stick the ERR CC-Lite and the ERR RailSounds Commander in the scale Williams 44-Tonner, and I even added electrocouplers.  Hard to imagine you can't stick the RS Commander into a significant larger locomotive.

Williams 44-Ton Upgrade with ERR CC-Lite, Sound, & Electrocouplers

You can bet I'm going to try and it should work.  I'm just looking at the printed dimensions of 1.25 wide.  I tried a standard DC commander for fit and it is 1.25 and it fit but with a slight drag on the sides.  Just reading so far, haven;r tried anything except the DC commander yet.  When I take the Bmann sound board out, that will free up some more length.  A 44 tonner is definitely a whole lot smaller.

Electrocouplers are in the plan, just have to decide which one.

All the ERR stuff fits into a 1.25" cavity with no issues.  I just measured the AC Commander (same board as the DC Commander), and it will fit.  You can also bend the heatsink in very slightly to eliminate the drag on the sides.  Of course, you could also consider the Mini-Commander II for this project, no problem fitting that one in!   The RS Commander is is also 1.25" wide and can be angled or placed vertically to fit it in.  Truthfully, this should be a pretty easy conversion.

FYI, measured the impedance of the speaker today and got 8 ohms.  Don't have to find a thin speaker that fits in the fuel tank, will use the factory one.

Also be careful on rewiring, depending on which truck you have, red is not always hot.  Verify with a meter.

Yep, especially with Williams stuff, they seem to have "flexible" color conventions.

gunrunnerjohn posted:

To give you an idea, here's one of my two LED parts boxes, probably at least a couple thousand LED's in there.

You can probably tell, I like lights on my trains!

When you go looking pick the size you'll need.  Here's a search for warm white flangeless LED. to get you started.

So much better than a box full of plastic bags. Guess I need toss some  fishing lures.  

   Both Michaels and Hobby Lobby sell glass staining paint (GREAT GLASS) in many colors I have found that you can significantly change the color of leds by dipping them in this stuff.  I even dip them multiple times in same and different colors.   The blue led is sold as cool white and was dipped in yellow great glass.         j

I can imagine that you can change them a bunch.  I used to use Tamiya clear paint to color bulbs, but I don't get much call for them nowadays.  I'm sure it would work on LED's as well.  Since LED's are so cheap, I just buy the color I need.